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Prog Retin Eye Res. Author manuscript; available in PMC 2018 July 01.

Published in final edited form as:
Prog Retin Eye Res. 2017 July ; 59: 158–177. doi:10.1016/j.preteyeres.2017.04.004.

Roles of Exosomes in the Normal and Diseased Eye

Mikael Klingeborn , W. Michael Dismuke , Catherine Bowes Rickman a,b , and W. Daniel
a
a
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Stamer a,c,*
a Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC 27710, USA
b Department of Cell Biology, Duke University, Durham, NC 27710, USA

c Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA

Abstract
Exosomes are nanometer-sized vesicles that are released by cells in a controlled fashion and
mediate a plethora of extra- and intercellular activities. Some key functions of exosomes include
cell-cell communication, immune modulation, extracellular matrix turnover, stem cell division/
differentiation, neovascularization and cellular waste removal. While much is known about their
role in cancer, exosome function in the many specialized tissues of the eye is just beginning to
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undergo rigorous study. Here we review current knowledge of exosome function in the visual
system in the context of larger bodies of data from other fields, in both health and disease.
Additionally, we discuss recent advances in the exosome field including use of exosomes as a
therapeutic vehicle, exosomes as a source of biomarkers for disease, plus current standards for
isolation and validation of exosome populations. Finally, we use this foundational information
about exosomes in the eye as a platform to identify areas of opportunity for future research
studies.

Keywords

exosome; extracellular vesicle; age-related macular degeneration; proteome; glaucoma; biomarker
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1. Exosomes: a brief overview

The endocytic pathway consists of compartments involved in the internalization of
extracellular ligands or cellular components, recycling of those components to the plasma
membrane, and/or their degradation (Gould & Lippincott-Schwartz 2009, Klumperman &
Raposo 2014). During the maturation process of early endosomes into late endosomes
(Stoorvogel et al. 1991), intraluminal vesicle (ILVs) accumulate. Because of their
appearance, these late endosomes are generally referred to as multivesicular endosomes
(MVE) or multivesicular bodies (MVBs). Loading of proteins, lipids, and cytosol into these

* Corresponding author: W. Daniel Stamer, Duke Eye Center, AERI Rm 4008, Durham, NC 27710, USA; Phone: 919-684-3745,
dan.stamer@duke.edu.
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